It runs eastward from the B4624 at Pont-tyweli, which lies on the Carmarthenshire side of the River Teifi across from Llandysul in Ceredigion, through Llanfihangel-ar-arth to Llanlliwni on the A485.

Before construction of the Llandysul bypass (opened in 2009), the B4336 began at a junction with the pre-bypass route of the A486 immediately south of the Teifi bridge. Now the first 450 metres of the original route have been subsumed into the B4624, and the B4436 begins at a junction with a newly built section of that road leading to the bypass.

The route follows the north bank of River Tyweli for 1.7 km before diverging to the left at Penlan to climb a gentle hill and then descend into Llanfihangel-an-arth where it crosses the B4459. Another climb, with good views across the valley of the Teifi to the left, brings the road to its terminus at the south end of the spread-out village of Llanllwni on the A485.